Separate the Wastewater Streams Before Selecting Equipment
A Tlaquepaque data center needs two treatment trains: a biological system for sanitary wastewater and a separate physical or membrane train for cooling-tower blowdown. Blowdown is the concentrated purge from the recirculating cooling loop, while sanitary wastewater comes from the data-center workforce. The parallel MBR treatment for sanitary wastewater should be sized from the domestic flow profile, not from the cooling-water balance. Keep the streams hydraulically separate because their contaminant profiles, treatment objectives and downstream reuse requirements differ.
The supplied Ecatepec guide, published by HydropureWater, treats sanitary wastewater as an MBR-compatible biological stream and cooling blowdown as a separate high-TDS train. It gives 80–120 L/person/day as the initial sanitary-generation screening figure; the project engineer must still confirm occupancy, shifts and the daily flow profile for the Tlaquepaque site. That figure is not a design flow.
RO membranes are not designed for the BOD and TSS variation associated with sanitary wastewater. Mixing the streams would also disturb the cooling-water chemical program and force both units to accept a feed for which they were not selected. Give each train its own flow meter, sampling point, chemical controls and discharge or reuse route.
| Design basis | Sanitary wastewater | Cooling-tower blowdown |
|---|---|---|
| Stream definition | Domestic wastewater generated by facility occupants | Concentrated liquid purge from the recirculating cooling loop |
| Initial planning input | 80–120 L/person/day, subject to site verification | No Tlaquepaque flow or cost is established in the supplied research |
| Primary treatment concept | Biological treatment, with MBR as the reference train | Filtration, chemical control and membrane treatment where required |
| Key design issue | BOD, TSS, nutrients and occupancy-driven flow variation | TDS, scaling, suspended solids and residual treatment chemicals |
Build the Tlaquepaque Water Balance from Operating Data
The design flow must come from a measured Tlaquepaque water balance, not from a generic data-center consumption ratio. Install meters for makeup water, blowdown, evaporation and emergency dumps, and record conductivity, pH, suspended solids and the complete cooling-water chemical history. Capture peak, average, minimum and emergency flows across normal and upset conditions; one monthly average will hide the events that control equipment size.
Cycles of concentration, or CoC, compare dissolved-solids concentration in circulating water with that in makeup water. Genesis Water Technologies explains that at 4 CoC, theoretical blowdown is 25% of makeup-water volume, calculated as 1/(CoC−1). The same source reports that actual blowdown may exceed theory by 15–30% because of unmeasured losses and emergency discharges. That operational allowance must be checked against site records rather than applied automatically.
Keep three quantities separate. Water consumption is water removed through evaporation or incorporated into products. Water usage includes water withdrawn and returned to its source, potentially after treatment. WUE divides annual site water usage by IT equipment energy, so it does not identify discharge quality or recoverable blowdown. A low WUE does not prove that the blowdown route is efficient.
The final mass balance should identify evaporation, recoverable blowdown, sanitary wastewater, demand for each reuse stream and residual discharge. It should also test whether proposed reuse exceeds the actual demand for cooling makeup, toilet flushing, irrigation or another identified service. No Tlaquepaque-specific flow, tariff or approved discharge route appears in the supplied research, so none should be assumed in the equipment budget.
Procurement gate: freeze the measured flow profile and water balance before bidders size filtration, UF, RO, MVC or crystallizer equipment.
Characterize Blowdown Before Membrane Selection
Blowdown chemistry determines whether the project can recover water for cooling and which pretreatment units are needed. The HydropureWater Ecatepec guide reports a screening range of 1,200–6,000 mg/L TDS, equivalent to 4–8 times makeup concentration. This is not a Tlaquepaque design value. Twelve months of site analysis is needed because source-water chemistry, cooling cycles and the chemical program determine the actual feed to each treatment unit.
Request TDS, hardness, silica, chloride, sulfate, iron and manganese data from both raw makeup and blowdown. Calcium, magnesium, silica and alkalinity concentrate as water evaporates; each has a saturation limit that constrains membrane recovery and concentrate handling. Iron and manganese can also foul membranes or precipitate after oxidation, so their behavior must be established from the supplied analysis and operating trend.
Suspended solids originate from corrosion products, biofilm fragments and airborne dust. The Ecatepec guide reports 10–50 mg/L in the basin despite side-stream filtration. That range is a screening observation from the supplied guide, not a measured value for Tlaquepaque. Filtration is therefore the first guard before membranes, but biological loading must also be controlled. The guide recommends cutting particulates below 10–15 µm before RO, with UF added where stronger biological and colloidal control is required.
The cooling-chemical inventory can change reuse acceptance as much as the inorganic analysis. Biocides, corrosion inhibitors, scale inhibitors and dispersants accumulate in the loop. Legacy chromate or high-phosphate programs introduce metals or nutrients that may complicate reuse or discharge. Ask for 12 months of chemical records, including product changes, dosages and any incidents.
| Parameter or source | Evidence from the supplied research | Procurement consequence |
|---|---|---|
| TDS and cycles of concentration | 1,200–6,000 mg/L and 4–8 times makeup in the Ecatepec guide | Screening only; obtain 12 months of Tlaquepaque data |
| Scaling species | Calcium, magnesium, silica and alkalinity | Set recovery, antiscalant and pretreatment limits after analysis |
| Suspended solids | 10–50 mg/L in the basin despite side-stream filtration in the supplied guide | Provide solids filtration and verify the membrane feed envelope |
| Residual chemistry | Biocides, inhibitors, dispersants, scale inhibitors, legacy chromate or high-phosphate programs | Assess reuse acceptance and complete chemical inventory |
| Biological growth | Bacteria, algae and biofilm organisms can foul membranes | Control biology before UF or RO; include biological monitoring |
Where biological control is required, an on-site chlorine-dioxide generation module may be evaluated subject to safety review, compatibility testing and the site’s chemical-control plan. It does not replace filtration, feed analysis or membrane warranty limits.
Choose the Pretreatment and Reuse Train
Side-stream filtration should remove suspended solids and reduce biological loading before any downstream membrane. The supplied Ecatepec guide cites a typical installed cost of $50,000–$200,000 for a data-center side-stream filtration installation, sourced there to genesiswatertech.com (2025). Use that only as a benchmark envelope; the Tlaquepaque bid must reflect flow, selected media, controls, solids handling and site installation costs.
Where the feed requires stronger biological, colloidal and solids control, use ultrafiltration pretreatment for cooling blowdown. The supplied guide gives 0.01–0.1 micron pore size, 10–30 psi operating pressure, 90–95% recovery and chemical cleaning every 1–3 months. Those figures describe the cited equipment concept, not a guarantee for site water.
RO is the principal unit when dissolved-solids removal is required for cooling makeup or another controlled reuse stream. The guide cites 95–99% TDS rejection, permeate at 10–50 mg/L TDS, 50–85% recovery and 150–400 psi operating pressure. A reverse-osmosis treatment module should be selected only after the vendor defines the allowable feed envelope, recovery basis and concentrate composition.
NF becomes relevant when partial softening or sulfate removal is required before RO. The supplied Ecatepec guide places NF at 75–150 psi and reports permeate at 30–50% of feed TDS. Multi-media filtration ahead of RO protects membranes from particulates; an multimedia pretreatment module can be evaluated as part of that train. Automatic antiscalant, biocide, pH-control or coagulant dosing should be coordinated through an automatic chemical-dosing system.
| Unit | Supplied benchmark | Primary use | Required confirmation |
|---|---|---|---|
| Side-stream filtration | $50,000–$200,000 installed for a typical data-center installation, genesiswatertech.com (2025) | Remove solids and reduce biological loading | Flow, media, backwash and solids-disposal design |
| UF | 0.01–0.1 micron; 10–30 psi; 90–95% recovery; cleaning every 1–3 months | Remove colloids, microorganisms and residual solids | Feed envelope, cleaning chemistry and reject handling |
| NF | 75–150 psi; permeate at 30–50% of feed TDS | Partial softening or sulfate removal | Hardness, sulfate, scaling and recovery calculations |
| RO | 95–99% TDS rejection; 10–50 mg/L permeate TDS; 50–85% recovery; 150–400 psi | Dissolved-solids removal for controlled reuse | Site water, pretreatment, antiscalant and concentrate disposal |
Candidate equipment modules do not replace process design. Require bidders to present the complete train, including pretreatment, chemical compatibility, redundancy, controls, cleaning access, reject routes and performance conditions.
Match Concentrate Management to the Discharge Route
The discharge route, not a generic ZLD preference, should determine the concentrate train. The supplied Ecatepec guide proposes side-stream filtration plus RO with 60–75% blowdown reuse where a permitted sewer outfall can accept the concentrate. That case depends on stable supply and confirmed sewer acceptance; it has not been established for Tlaquepaque.
If discharge volume is constrained but liquid discharge remains permitted, evaluate partial zero liquid discharge: RO followed by mechanical vapor compression, or MVC. The guide reports 85–95% overall recovery for the combined train without a crystallizer. The MVC benchmark is 10,000–30,000 GPD capacity, $1–3 million installed cost, 15–25 kWh per 1,000 US gallons, 95–98% recovery and distillate TDS below 10 mg/L.
If no liquid discharge route is available, compare full ZLD with a crystallizer. The guide cites 95–99% overall recovery, $3–8 million capital cost and $5–15 per thousand gallons operating cost. It also cites a 50,000 GPD RO installation at $250,000–$500,000 installed and $1.50–$3.00 per thousand gallons operating cost. These figures are sourced benchmarks, not Tlaquepaque quotations, and they must be reconciled to the same flow and cost basis in each bid.
| Discharge condition | Candidate train | Supplied benchmark | Decision still required |
|---|---|---|---|
| Permitted sewer or controlled discharge | Side-stream filtration plus RO | 60–75% blowdown reuse | Confirm permit, sewer capacity and concentrate limits |
| Restricted liquid discharge, but liquid discharge remains permitted | RO plus MVC, partial ZLD | 85–95% overall recovery; MVC costs and performance as cited above | Verify residual liquid route and energy demand |
| No liquid discharge available | RO plus MVC plus crystallizer, full ZLD | 95–99% overall recovery; $3–8 million capital cost; $5–15 per thousand gallons operating cost | Confirm residue classification, handling route and disposal capacity |
| RO reference case | 50,000 GPD RO | $250,000–$500,000 installed; $1.50–$3.00 per thousand gallons operating cost | Re-bid against measured Tlaquepaque flows |
The business case should include water purchase, avoided discharge fees, energy, chemicals, maintenance, membrane replacement and concentrate or residue disposal. Do not assume a local tariff. More recovery adds equipment and operating burden, so the selected pathway must follow from the verified discharge constraint and the value of recovered water.
Make the Decision from Site Conditions
The preferred train changes with discharge access, allocation risk, reuse demand and operating capability. Where supply is stable and discharge permission is obtainable, start with side-stream filtration plus RO and test the 60–75% blowdown-reuse case identified in the supplied Ecatepec guide. Where allocation is contested or discharge volume is restricted, evaluate NF for partial softening and MVC treatment of RO concentrate as partial ZLD. Where no liquid discharge is available or a water-positive objective requires it, compare full ZLD with crystallizer against avoided water purchase and discharge costs.
Lifecycle impacts must be included. The 2026 Open Engineering study, “Reclaiming Cooling: Wastewater Reuse as a Strategic Resource for Data Center Water Management,” reports approximately twice the global warming potential for its wastewater scenario compared with freshwater. Roughly 80% of that difference is attributable to treatment energy. The study also reports an indirect water penalty of approximately 0.93 L/m³, less than 0.1% of the direct displacement benefit.
Require each bidder to use the same measured site basis. Its proposal should disclose recovery, concentrate volume, cleaning frequency, membrane replacement, energy, chemical consumption and disposal assumptions. Competitive quotes should distinguish equipment supply from a warranted process, and should state every utility or operator prerequisite.
| Site condition | Decision | Evidence to request |
|---|---|---|
| Stable supply and obtainable discharge permission | Evaluate side-stream filtration plus RO and 60–75% reuse | Permit pathway, concentrate analysis and guaranteed recovery |
| Contested allocation or partial discharge restrictions | Add NF; evaluate MVC treatment of RO concentrate | Allocation evidence, liquid-discharge route and energy model |
| No liquid discharge or water-positive objective | Compare full ZLD with crystallizer | Residue volume, classification, handler and disposal terms |
Verify Permissions and Obtain Site-Specific Inputs
Confirm the destination of every stream before purchasing equipment. The sanitary train may discharge to a sanitary sewer or follow a separate reuse route. The blowdown train may feed on-site non-potable reuse, irrigation, a permitted industrial sewer, partial ZLD with a liquid concentrate discharge, or full ZLD with solid-residue management. Each route needs its own approval evidence; treatment performance alone does not create discharge authorization.
Verify applicable NOM-001-SEMARNAT conditions and other current requirements with the relevant authority and local counsel. The supplied research does not establish current limit values, Tlaquepaque discharge tariffs, current reuse rules or the conditions of any particular permit. Also confirm water-allocation and extraction constraints affecting cooling makeup, sewer-acceptance requirements and the rules governing each proposed reuse application. Do not transfer Ecatepec assumptions to Tlaquepaque without written confirmation.
The owner should provide bidders with 12 months of raw-makeup and blowdown analysis covering TDS, hardness, silica, chloride, sulfate, iron, manganese, TSS, pH and temperature. Include the complete cooling-chemical inventory, operating logs, meter data and emergency-discharge records. Those records define the feed envelope, chemical-compatibility requirements and basis of design.
Then require performance guarantees tied to that envelope: RO recovery, permeate TDS, membrane life, UF cleaning frequency, chemical consumption and equipment availability. Where MVC is proposed, require specific energy use and distillate quality. Where a crystallizer is proposed, require residue volume, composition, sampling method and a lawful disposal route. A bidder guarantee that cannot be audited against site inputs is not a guarantee worth accepting.
Close the gap between generic guidance and a purchase order: confirm the route, verify the permit, measure the stream and bind every guarantee to the verified site condition.
Frequently Asked Questions
How should wastewater and cooling blowdown treatment be sized for a data center in Tlaquepaque?
Size the sanitary and blowdown trains separately. The sanitary bid must use occupancy, shift schedules and the 80–120 L/person/day screening figure identified in the supplied HydropureWater Ecatepec guide, then adjust it with measured flows. The blowdown bid must use peak, average, minimum and emergency flow data, measured makeup and evaporation, 12 months of water chemistry and the cooling-water chemical inventory. Cooling capacity or site area alone is not a defensible sizing basis.
What should a bidder include in its wastewater-treatment price for Tlaquepaque?
Request a priced process basis tied to the site water analysis rather than a generic per-gallon estimate. As screening benchmarks only, the supplied guide cites $50,000–$200,000 for typical side-stream filtration, $250,000–$500,000 installed for a 50,000 GPD RO system with $1.50–$3.00 per thousand gallons operating cost, and $3–8 million capital cost with $5–15 per thousand gallons operating cost for full ZLD. These are sourced benchmarks, not local quotations. The bid should separately price equipment, installation, energy, chemicals, maintenance, membrane replacement, concentrate disposal and residue management.
Should sanitary wastewater be combined with cooling-tower blowdown?
No. Sanitary wastewater carries BOD, TSS and nutrient swings that are incompatible with the high-TDS blowdown train, while commingling would also disturb the cooling-water chemical program. Keep parallel MBR treatment for sanitary wastewater separate from filtration and membrane treatment for blowdown. Use the 80–120 L/person/day figure only for preliminary sanitary screening until occupancy and flow records are available.
What must be verified before selecting an RO or ZLD system?
Verify the legal route with the relevant authority and local counsel, including applicable NOM-001-SEMARNAT conditions, current reuse rules, water-allocation constraints and sewer acceptance. Obtain 12 months of raw-makeup and blowdown analysis, complete chemical records and measured flow data. Then require guarantees for RO recovery and permeate TDS, membrane life, UF cleaning, MVC specific energy where applicable, and crystallizer residue volume where applicable. Technical treatment performance does not replace authorization to discharge or reuse the water.